Abstract: A process for the preparation of hexafluoropropene by thermal cleavage of chlorotetrafluoroethane and/or chlorohexafluoropropane or a mixture of chlorotetrafluoroethane and perfluorocyclobutane at 600.degree. to 1,000.degree. C. and under a pressure of 1 to 1,000 kPa is described. The thermal cleavage is carried out in the presence of at least 0.05 mole of tetrafluoroethylene per mole of chlorotetrafluoroethane and/or chlorohexafluoropropane or mixture of chlorotetrafluoroethane and perfluorocyclobutane employed. By means of this process hexafluoropropene is obtained for a small extra expenditure on apparatus at a good selectivity and in an improved space-time yield.

Abstract: A process is described for the production of pure tetrafluoroethylene from a gas formed in the pyrolysis of a fluorocarbon compound having 1 to 4 carbon atoms, which can contain a hydrogen atom and a chlorine atom. The pyrolysis gas, after hydrogen chloride or hydrogen fluoride and also if necessary steam have been separated off, is condensed under pressure and distilled in a plurality of columns, in the first column the low boilers being distilled off, preferably with a reflux ratio of 6 to 15 kg per kg of tetrafluoroethylene produced, and in the second column tetrafluoroethylene, preferably with a reflux ratio of 3 to 5 kg per kg of tetrafluoroethylene produced. Per kg of tetrafluoroethylene produced, from 0.6 to 2 kg of difluoromonochloromethane are fed into the second column as a distillation aid. The novel process makes it possible to produce pure tetrafluoroethylene at comparatively reduced energy and apparatus costs.